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Land-use Change (land-use + change)
Selected AbstractsK. P. Bell, K. J. Boyle and J. Rubin (eds.): Economics of Rural Land-Use ChangeJOURNAL OF AGRICULTURAL ECONOMICS, Issue 2 2007Cesar L. Revoredo Giha No abstract is available for this article. [source] Leaf dry matter content and lateral spread predict response to land use change for six subalpine grassland speciesJOURNAL OF VEGETATION SCIENCE, Issue 2 2007Nicolas Gross Abstract Question: Land-use change has a major impact on terrestrial plant communities by affecting fertility and disturbance. We test how particular combinations of plant functional traits can predict species responses to these factors and their abundance in the field by examining whether trade-offs at the trait level (fundamental trade-offs) are linked to trade-offs at the response level (secondary trade-offs). Location: Central French Alps. Methods: We conducted a pot experiment in which we characterized plant trait syndromes by measuring whole plant and leaf traits for six dominant species, originating from contrasting subalpine grassland types. We characterized their response to nutrient availability, shading and clipping. We quantified factors linked with different land usage in the field to test the relevance of our experimental treatments. Results: We showed that land management affected nutrient concentration in soil, light availability and disturbance intensity. We identified particular suites of traits linked to plant stature and leaf structure which were associated with species responses to these environmental factors. Leaf dry matter content separates fast and slow growing species. Height and lateral spread separated tolerant and intolerant species to shade and clipping. Discussion and Conclusion: Two fundamental trade-offs based on stature traits and leaf traits were linked to two secondary trade-offs based on response to fertilization shade and mowing. Based on these trade-offs, we discuss four different species strategies which could explain and predict species distributions and traits syndrome at community scale under different land-uses in subalpine grasslands. [source] Managerial failure in late Victorian Britain?: Land use and English agricultureECONOMIC HISTORY REVIEW, Issue 2 2001E.H. Hunt This article focuses upon the neglected role of agriculture in Britain's relative economic decline. Landlords and farmers stand accused of responding inadequately to the flood of American cereal imports. Land-use changes are analysed by soil type and access to urban markets, revealing a range of opportunities and restraints, and an appropriate variety of responses. Other aspects of agriculturalists' responses to depression remain to be examined, but this exercise finds no evidence of significant managerial shortcomings. Rather, the interim verdict is similar to that on the performance of those British industrialists whose once-savaged reputations have been partly redeemed by the researches of McCloskey, Sandberg, et al. [source] Land-cover and land-use change and its contribution to the large-scale organization of Puerto Rico's bird assemblagesDIVERSITY AND DISTRIBUTIONS, Issue 1 2008Miguel A. Acevedo ABSTRACT Global biodiversity is changing rapidly driven by human alteration of habitat, and nowhere this is more dramatic than in insular habitats. Yet land-cover change is a complex phenomenon that not only involves habitat destruction but also forest recovery over different time scales. Therefore, we might expect species to respond in diverse ways with likely consequences for the reorganization of regional assemblages. These changes, however, may be different in tropical islands because of their low species richness, generalist habits and high proportion of endemics. Here, we focus on the island of Puerto Rico and ask how island-wide changes in land cover and land use has influenced the large-scale organization of bird assemblages. To address this question, we combined in a Geographical Information System (GIS) the first 6 years (1997,2002) of the Puerto Rican Breeding Bird Survey (PR-BBS) with land-cover and land-use data extracted from a published digital map derived from the classification of Landsat images. A Non-metric Multidimensional Scaling (NMS) ordination based on the composition and abundance of birds, and percentage land-use types showed that land use followed by climate could explain most of the variation observed among routes in terms of species composition and abundance. Moreover, endemic and exotic species were widely distributed throughout the island, but the proportion of endemic species is higher in closed forests while exotic species are more abundant in open habitats. However, historical accounts from the early 1900s indicate that endemic species were distributed across the entire island. Today, most of the land cover transformation in Puerto Rico occurs in the lowlands which may explain the high abundance of endemic species in cloud forests and the high abundance of exotic species in open habitats in the lowlands. [source] Sediment transmission and storage: the implications for reconstructing landform developmentEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2010R. C. Chiverrell Abstract The late Holocene (last 3000 years) development of the lower Ribble valley (northwest England) displays evidence for a complex response to a sediment recharge event forced by land-use change induced increases in erosion and sediment delivery. The deposition of fluvial sediments during the late Holocene was restricted to a series of reaches or depocenters separated by zones with no sediment accumulation constrained by older glacial and fluvial terrain. Apparent reach-wide correlations of fluvial terraces break down under the scrutiny applied by comprehensive and extensive radiocarbon control. Bayesian testing of relative order models show that large-scale geomorphological changes, e.g. the progression from one terrace level to another, were time transgressive between different depocenters. The different histories of sediment delivery and storage are probably a function of local- and process-scale variations in these depocenters, and reflect (dis)connectivity relationships within a reach in propagating a basin-scale change (superslug) in the sediment regime. Disconnectivity in the depositional regime through a fluvial reach limits what we can reconstruct in terms of sediment budgets, but radiocarbon dating of multiple palaeochannels offers considerable potential for landform-based research to uncover rates of change within individual depocenters. Copyright © 2009 John Wiley & Sons, Ltd. [source] Post-European settlement response gradients of river sensitivity and recovery across the upper Hunter catchment, AustraliaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2009Kirstie Fryirs Abstract Most analyses of river adjustment have focused on parts of catchments where metamorphosis has occurred. This provides a non-representative view of river responses to human-disturbance. Although many rivers have been subjected to systematic land-use change and disturbance, significant variability is evident in the form, extent and consequences of adjustment. This study documents the catchment-wide distribution of river sensitivity and adjustment in the upper Hunter catchment, New South Wales, Australia in the period since European settlement. The spatial distribution and timing of lateral, vertical and wholesale river adjustments are used to assess river sensitivity to change. The type and pattern of rivers, influenced largely by valley setting, have induced a fragmented pattern of river adjustment in the upper Hunter catchment. Adjustments have been largely non-uniform and localized, reflecting the predominance of bedrock-controlled rivers which have limited capacity to adjust and are resilient to change. Less than 20% of river courses have experienced metamorphosis. Phases of reach-scale geomorphic adjustment to human disturbance are characterized as a gradient of primary, secondary and tertiary responses. In general terms, primary responses such as cutoffs or straightening were followed by secondary responses such as channel expansion. These secondary responses occurred between 50,70 years after initial disturbance. A subsequent tertiary phase of river recovery, denoted as a transition from predominantly erosional to predominantly depositional geomorphic processes such as channel contraction, occurred around 70,120 years after initial disturbance. Such responses are ongoing across much of the upper Hunter catchment. Copyright © 2009 John Wiley & Sons, Ltd. [source] Response of collembolan communities to land-use change and grassland successionECOGRAPHY, Issue 2 2007Matthieu Chauvat This study focuses on the long-term changes of collembolan communities occurring after the conversion of arable land to managed grassland. We analysed collembolan communities at grassland sites of different age that had been gradually converted over a period of 50 yr. Abundance and biomass responded rapidly and very positively to the conversion of arable land to grassland, while species richness was not affected. Collembolan assemblages changed only little during grassland maturation. The impact of land-use change on community structure was more obvious at the functional level because the colonization processes observed in our study mostly relied on hemiedaphic species. Vegetation and soil parameters were good predictors of collembolan community structure during development of managed grassland. The present study demonstrated that past landscape patterns and processes like land-use conversion and subsequent succession had a considerable impact on the present day pattern of species richness and community composition of Collembola within a landscape. Our results strongly differ from those obtained for other invertebrate groups, highlighting on the one hand the very diverse reactions of invertebrates to a common factor, and on the other hand the need to survey more than one taxa in order to draw conclusions on effects of land-use change on faunistic communities. [source] Evidence-based policy or policy-based evidence gathering?ENVIRONMENTAL POLICY AND GOVERNANCE, Issue 5 2010Biofuels, the 10% target, the EU Abstract The 2009 Renewable Energy Directive mandates EU member-states' road transport fuel to comprise a minimum of 10% renewable content by 2020. This target is expected to be met predominantly from biofuels. However, scientific evidence is increasingly questioning the ability of biofuels to reduce greenhouse gas emissions when factors such as indirect land-use change are taken into consideration. This paper interrogates the 10% target, critically assessing its political motivations, use of scientific evidence and the actions of an individual policy entrepreneur who played a central role in its adoption. We find that the commitment of EU decision-making bodies to internal guidelines on the use of expertise and the precautionary principle was questionable, despite the scientific uncertainty inherent in the biofuels debate. Imperatives located in the political space dominated scientific evidence and led to a process of ,policy-based evidence gathering' to justify the policy choice of a 10% renewable energy/biofuels target. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment. [source] Litter species composition influences the performance of seedlings of grassland herbsFUNCTIONAL ECOLOGY, Issue 3 2006H. QUESTED Summary 1This study examines the impacts of plant litter species identity and the composition of litter mixtures on seedling recruitment in the context of land-use change (abandonment) in conservationally important southern Swedish semi-natural grasslands. 2We found that plant litter had marked positive effects on the seedling recruitment of two common grassland species, and that these effects varied strongly with the species identity of the litter. 3There was no consistent evidence that litters of species typical of earlier succession had a greater positive impact on recruitment than those typical of late succession. 4The impact of mixtures of the five litter types examined was generally as expected based on the impacts of single-species litters and their contribution to the litter mixture, as predicted by the biomass ratio hypothesis. However, this was not the case for all litter and seedling species combinations, and some interactions were evident. 5Species identity of litter is important even in multispecies litter mixtures. Changes in plant species dominance (and hence the proportions of litter of different species), as a result of shifts in land use, are likely to result in changes in seedling performance, with potential consequences for the persistence of plant populations in former semi-natural grasslands. [source] FIGHTING FIRE WITH A BROKEN TEACUP: A COMPARATIVE ANALYSIS OF SOUTH AFRICA'S LAND-REDISTRIBUTION PROGRAM,GEOGRAPHICAL REVIEW, Issue 3 2008WILLIAM G. MOSELEY ABSTRACT. Since the rise of its first democratically elected government in 1994, South Africa has sought to redress its highly inequitable land distribution through a series of land-reform programs. In this study we examine land-redistribution efforts in two of South Africa's provinces, the Western Cape and Limpopo. By analyzing a cross-section of projects in these two locales we develop a political ecology of stymied land-reform possibilities to explain the limited progress to date. Given South Africa's ambitious goal of redistributing 30 percent of its white-owned land by 2014 and the incremental and flawed nature of its redistribution program, we argue that the process is like trying to put out a fire with a broken teacup. Our results are based on interviews with policymakers, commercial farmers, and land-redistribution beneficiaries, as well as on an analysis of land-use change in Limpopo Province. [source] LAND-USE DYNAMICS BEYOND THE AMERICAN URBAN FRINGE,GEOGRAPHICAL REVIEW, Issue 3 2001DAVID M. THEOBALD ABSTRACT. A deficiency common to both the historical debates over loss of agricultural land and the current discussions of urbanization and sprawl is a limited understanding of land-use dynamics beyond the urban fringe. Data aggregated at the county level poorly capture the fine-grained pattern of land-use change beyond the dynamic urban-rural interface. Furthermore, current urban-based definitions are poorly suited to delineate these areas, and low-density, exurban land use is difficult to measure using existing land-cover databases. Urbanization and the conversion of once-agricultural or other natural resource lands to other uses has traditionally been tracked using urban areas, as delimited in the U.S. census. Urban densities are typically defined as areas with more than 1,000 people per square mile, or 1.6 people per acre (U.S. Census Bureau 2000). Assuming an average of 2.5 people per housing unit, this translates to roughly 0.7 units per acre, or approximately 1 unit per 1.6 acres. The analytical units used in the census, however, both overbound and underbound areas with urban densities. About one-third of urban areas in 1990 comprised lower-than-urban housing density, thanks to overbounding. But, then, one-third of locations that had urban-level housing densities failed to be included in urban areas as a result of underbounding, which, if counted, would have constituted another 18 million acres of urban area. An increase over time of the average number of acres required per housing unit in exurban and higher-density locations occurred in roughly one-third of U.S. counties from 1960 to 1990 and persisted from 1990 to 2000. In 2000 roughly 38 million acres were settled at urban densities, and nearly ten times that much land was settled at rates from low, exurban density (as low as one house per 40 acres) to higher rates (up to one per 10 acres). This represents a continuing encroachment on land previously given over to other uses,habitat or agriculture. Practitioners of natural resource management need to recognize the ubiquity of exurban development and better incorporate the fine-scale patterns of land use beyond the urban fringe. [source] Soil,atmosphere exchange of CH4, CO, N2O and NOx and the effects of land-use change in the semiarid Mallee system in Southeastern AustraliaGLOBAL CHANGE BIOLOGY, Issue 9 2010IAN GALBALLY Abstract The semiarid and arid zones cover a quarter of the global land area and support one-fifth of the world's human population. A significant fraction of the global soil,atmosphere exchange for climatically active gases occurs in semiarid and arid zones yet little is known about these exchanges. A study was made of the soil,atmosphere exchange of CH4, CO, N2O and NOx in the semiarid Mallee system, in north-western Victoria, Australia, at two sites: one pristine mallee and the other cleared for approximately 65 years for farming (currently wheat). The mean (± standard error) rates of CH4 exchange were uptakes of ,3.0 ± 0.5 ng(C) m,2 s,1 for the Mallee and ,6.0 ± 0.3 ng(C) m,2 s,1 for the Wheat. Converting mallee forest to wheat crop increases CH4 uptake significantly. CH4 emissions were observed in the Mallee in summer and were hypothesized to arise from termite activity. We find no evidence that in situ growing wheat plants emit CH4, contrary to a recent report. The average CO emissions of 10.1 ± 1.8 ng(C) m,2 s,1 in the Mallee and 12.6 ± 2.0 ng(C) m,2 s,1 in the Wheat. The average N2O emissions were 0.5 ± 0.1 ng(N) m,2 s,1 from the pristine Mallee and 1.4 ± 0.3 ng(N) m,2 s,1 from the Wheat. The experimental results show that the processes controlling these exchanges are different to those in temperate systems and are poorly understood. [source] Monoterpene emissions from rubber trees (Hevea brasiliensis) in a changing landscape and climate: chemical speciation and environmental controlGLOBAL CHANGE BIOLOGY, Issue 11 2007YONG-FENG WANG Abstract Emissions of biogenic volatile organic compounds (VOCs) have important roles in ecophysiology and atmospheric chemistry at a wide range of spatial and temporal scales. Tropical regions are a major global source of VOC emissions and magnitude and chemical speciation of VOC emissions are highly plant-species specific. Therefore it is important to study emissions from dominant species in tropical regions undergoing large-scale land-use change, for example, rubber plantations in South East Asia. Rubber trees (Hevea brasiliensis) are strong emitters of light-dependent monoterpenes. Measurements of emissions from leaves were made in the dry season in February 2003 and at the beginning of the wet season in May 2005. Major emitted compounds were sabinene, , -pinene and , -pinene, but , -ocimene and linalool also contributed significantly at low temperature and light. Cis -ocimene was emitted with a circadian course independent of photosynthetic active radiation (PAR) and temperature changes with a maximum in the middle of the day. Total isoprenoid VOC emission potential at the beginning of the wet season (94 ,g gdw,1 h,1) was almost two orders of magnitude higher than measured in the dry season (2 ,g g dw,1 h,1). Composition of total emissions changed with increasing temperature or PAR ramps imposed throughout a day. As well as light and temperature, there was evidence that assimilation rate was also a factor contributing to seasonal regulating emission potential of monoterpenes from rubber trees. Results presented here contribute to a better understanding of an important source of biogenic VOC associated with land-use change in tropical South East Asia. [source] Projecting future N2O emissions from agricultural soils in BelgiumGLOBAL CHANGE BIOLOGY, Issue 1 2007CAROLINE ROELANDT Abstract This study analyses the spatial and temporal variability of N2O emissions from the agricultural soils of Belgium. Annual N2O emission rates are estimated with two statistical models, MCROPS and MGRASS, which take account of the impact of changes in land use, climate, and nitrogen-fertilization rate. The models are used to simulate the temporal trend of N2O emissions between 1990 and 2050 for a 10, latitude and longitude grid. The results are also aggregated to the regional and national scale to facilitate comparison with other studies and national inventories. Changes in climate and land use are derived from the quantitative scenarios developed by the ATEAM project based on the Intergovernmental Panel on Climate Change-Special Report on Emissions Scenarios (IPCC-SRES) storylines. The average N2O flux for Belgium was estimated to be 8.6 × 106 kg N2O-N yr,1 (STD = 2.1 × 106 kg N2O-N yr,1) for the period 1990,2000. Fluxes estimated for a single year (1996) give a reasonable agreement with published results at the national and regional scales for the same year. The scenario-based simulations of future N2O emissions show the strong influence of land-use change. The scenarios A1FI, B1 and B2 produce similar results between 2001 and 2050 with a national emission rate in 2050 of 11.9 × 106 kg N2O-N yr,1. The A2 scenario, however, is very sensitive to the reduction in agricultural land areas (,14% compared with the 1990 baseline), which results in a reduced emission rate in 2050 of 8.3 × 106 kg N2O-N yr,1. Neither the climatic change scenarios nor the reduction in nitrogen fertilization rate could explain these results leading to the conclusion that N2O emissions from Belgian agricultural soils will be more markedly affected by changes in agricultural land areas. [source] Climate- and crop-responsive emission factors significantly alter estimates of current and future nitrous oxide emissions from fertilizer useGLOBAL CHANGE BIOLOGY, Issue 9 2005Helen C. Flynn Abstract The current Intergovernmental Panel on Climate Change (IPCC) default methodology (tier 1) for calculating nitrous oxide (N2O) emissions from nitrogen applied to agricultural soils takes no account of either crop type or climatic conditions. As a result, the methodology omits factors that are crucial in determining current emissions, and has no mechanism to assess the potential impact of future climate and land-use change. Scotland is used as a case study to illustrate the development of a new methodology, which retains the simple structure of the IPCC tier 1 methodology, but incorporates crop- and climate-dependent emission factors (EFs). It also includes a factor to account for the effect of soil compaction because of trampling by grazing animals. These factors are based on recent field studies in Scotland and elsewhere in the UK. Under current conditions, the new methodology produces significantly higher estimates of annual N2O emissions than the IPCC default methodology, almost entirely because of the increased contribution of grazed pasture. Total emissions from applied fertilizer and N deposited by grazing animals are estimated at 10 662 t N2O-N yr,1 using the newly derived EFs, as opposed to 6 796 t N2O-N yr,1 using the IPCC default EFs. On a spatial basis, emission levels are closer to those calculated using field observations and detailed soil modelling than to estimates made using the IPCC default methodology. This can be illustrated by parts of the western Ayrshire basin, which have previously been calculated to emit 8,9 kg N2O-N ha,1 yr,1 and are estimated here as 6.25,8.75 kg N2O-N ha,1 yr,1, while the IPCC default methodology gives a maximum emission level of only 3.75 kg N2O-N ha,1 yr,1 for the whole area. The new methodology is also applied in conjunction with scenarios for future climate- and land-use patterns, to assess how these emissions may change in the future. The results suggest that by 2080, Scottish N2O emissions may increase by up to 14%, depending on the climate scenario, if fertilizer and land management practices remain unchanged. Reductions in agricultural land use, however, have the potential to mitigate these increases and, depending on the replacement land use, may even reduce emissions to below current levels. [source] Quantifying uncertainty in estimates of C emissions from above-ground biomass due to historic land-use change to cropping in AustraliaGLOBAL CHANGE BIOLOGY, Issue 8 2001Damian J. Barrett Abstract Quantifying continental scale carbon emissions from the oxidation of above-ground plant biomass following land-use change (LUC) is made difficult by the lack of information on how much biomass was present prior to vegetation clearing and on the timing and location of historical LUC. The considerable spatial variability of vegetation and the uncertainty of this variability leads to difficulties in predicting biomass C density (tC ha,1) prior to LUC. The issue of quantifying uncertainties in the estimation of land based sources and sinks of CO2, and the feasibility of reducing these uncertainties by further sampling, is critical information required by governments world-wide for public policy development on climate change issues. A quantitative statistical approach is required to calculate confidence intervals (the level of certainty) of estimated cleared above-ground biomass. In this study, a set of high-quality observations of steady state above-ground biomass from relatively undisturbed ecological sites across the Australian continent was combined with vegetation, topographic, climatic and edaphic data sets within a Geographical Information System. A statistical model was developed from the data set of observations to predict potential biomass and the standard error of potential biomass for all 0.05° (approximately 5 × 5 km) land grid cells of the continent. In addition, the spatial autocorrelation of observations and residuals from the statistical model was examined. Finally, total C emissions due to historic LUC to cultivation and cropping were estimated by combining the statistical model with a data set of fractional cropland area per land grid cell, fAc (Ramankutty & Foley 1998). Total C emissions from loss of above-ground biomass due to cropping since European colonization of Australia was estimated to be 757 MtC. These estimates are an upper limit because the predicted steady state biomass may be less than the above-ground biomass immediately prior to LUC because of disturbance. The estimated standard error of total C emissions was calculated from the standard error of predicted biomass, the standard error of fAc and the spatial autocorrelation of biomass. However, quantitative estimates of the standard error of fAc were unavailable. Thus, two scenarios were developed to examine the effect of error in fAc on the error in total C emissions. In the first scenario, in which fAc was regarded as accurate (i.e. a coefficient of variation, CV, of fAc = 0.0), the 95% confidence interval of the continental C emissions was 379,1135 MtC. In the second scenario, a 50% error in estimated cropland area was assumed (a CV of fAc = 0.50) and the estimated confidence interval increased to between 350 and 1294 MtC. The CV of C emissions for these two scenarios was 25% and 29%. Thus, while accurate maps of land-use change contribute to decreasing uncertainty in C emissions from LUC, the major source of this uncertainty arises from the prediction accuracy of biomass C density. It is argued that, even with large sample numbers, the high cost of sampling biomass carbon may limit the uncertainty of above-ground biomass to about a CV of 25%. [source] Spatial and temporal dynamics of methane emissions from agricultural sources in ChinaGLOBAL CHANGE BIOLOGY, Issue 1 2001Peter H. Verburg Summary Agricultural activities contribute significantly to the global methane budget. Agricultural sources of methane are influenced by land-use change, including changes in agricultural area, livestock keeping and agricultural management practices. A spatially explicit inventory of methane emissions from agriculture is made for China taking the interconnections between the different agricultural sources into account. The influence of land-use change on methane emissions is studied by linking a dynamic land-use change model with emission calculations. The land-use change model calculates changes in rice area and livestock numbers for a base-line scenario. Emissions are calculated for 1991 based on land-use statistics and for 2010 based on simulated changes in land-use patterns. Emissions from enteric fermentation and manure management are based on emission factors, while emissions from rice paddies involve the calculation of total organic carbon added to rice paddy soils and assume that a constant fraction is emitted as methane. Spatial patterns of emissions are presented for the different sources. For the land-use scenario considered it is expected that total methane emissions from agricultural sources in China increase by 11% while the relative contribution of rice fields to the emission decreases. Emissions from manure management are expected to become more important. These results indicate that agencies should anticipate changes in source strengths as a consequence of land-use changes when proposing mitigation strategies and future national greenhouse gas budgets. [source] What does species richness tell us about functional trait diversity?GLOBAL ECOLOGY, Issue 4 2010Predictions, evidence for responses of species, functional trait diversity to land-use change ABSTRACT In the conservation literature on land-use change, it is often assumed that land-use intensification drives species loss, driving a loss of functional trait diversity and ecosystem function. Modern research, however, does not support this cascade of loss for all natural systems. In this paper we explore the errors in this assumption and present a conceptual model taking a more mechanistic approach to the species,functional trait association in a context of land-use change. We provide empirical support for our model's predictions demonstrating that the association of species and functional trait diversity follows various trajectories in response to land-use change. The central premise of our model is that land-use change impacts upon processes of community assembly, not species per se. From the model, it is clear that community context (i.e. type of disturbance, species pool size) will affect the response trajectory of the relationship between species and functional trait diversity in communities undergoing land-use change. The maintenance of ecosystem function and of species diversity in the face of increasing land-use change are complementary goals. The use of a more ecologically realistic model of responses of species and functional traits will improve our ability to make wise management decisions to achieve both aims in specific at-risk systems. [source] Soil organic carbon storage in grazing pasture converted from forest on Andosol soilGRASSLAND SCIENCE, Issue 4 2007Shigeo Takahashi Abstract In order to clarify the effect of land-use change from forest to grazing pasture on the organic carbon storage in Andosol soil, the Rothamsted carbon turnover model for volcanic soil was applied to a pasture situated at the National Livestock Breeding Center (37°09,N, 140°03,E). The top 25-cm soil layer was considered to be an active soil carbon pool. The carbon storage in the soils of native forest surrounding the pastures ranged 111,163 t C ha,1 with an average of 133 t C ha,1, which was adjusted according to an equivalent soil weight of pasture. The pasture soil carbon stocks ranged 88,135 t C ha,1, with variations according to site and/or pasture age. The carbon inputs to the soil through the above- and below-ground dead material from pasture plants and cattle feces were estimated to be 1.1, 1.8 and 0.9 t C ha,1 year,1, respectively. As the model outputs of 14C content of the soil, which is an index of carbon dating corresponding to nuclear weapons testing, showed a relatively close agreement with the observations, the modeling was acceptable for the purpose of predicting the turnover of organic carbon in Andosol soil. The model simulation demonstrated that, in order to maintain the average forest carbon level, 3,4 t ha,1 year,1 of the organic carbon input would be needed. These inputs would be provided in a grazing pasture producing 8,9 t ha,1 year,1 of above-ground dry matter. [source] Modelling the hydrologic effects of dynamic land-use change using a distributed hydrologic model and a spatial land-use allocation modelHYDROLOGICAL PROCESSES, Issue 18 2010Hone-Jay Chu Abstract This study develops a novel approach for modelling and examining the impacts of time,space land-use changes on hydrological components. The approach uses an empirical land-use change allocation model (CLUE-s) and a distributed hydrological model (DHSVM) to examine various land-use change scenarios in the Wu-Tu watershed in northern Taiwan. The study also uses a generalized likelihood uncertainty estimation approach to quantify the parameter uncertainty of the distributed hydrological model. The results indicate that various land-use policies,such as no change, dynamic change and simultaneous change,have different levels of impact on simulating the spatial distributions of hydrological components in the watershed study. Peak flow rates under simultaneous and dynamic land-use changes are 5·71% and 2·77%, respectively, greater than the rate under the no land-use change scenario. Using dynamic land-use changes to assess the effect of land-use changes on hydrological components is more practical and feasible than using simultaneous land-use change and no land-use change scenarios. Furthermore, land-use change is a spatial dynamic process that can lead to significant changes in the distributions of ground water and soil moisture. The spatial distributions of land-use changes influence hydrological processes, such as the ground water level of whole areas, particularly in the downstream watershed. Copyright © 2010 John Wiley & Sons, Ltd. [source] Evaluating explicit and implicit routing for watershed hydro-ecological models of forest hydrology at the small catchment scaleHYDROLOGICAL PROCESSES, Issue 8 2001C. L. Tague Abstract This paper explores the behaviour and sensitivity of a watershed model used for simulating lateral soil water redistribution and runoff production. In applications such as modelling the effects of land-use change in small headwater catchments, interactions between soil moisture, runoff and ecological processes are important. Because climate, soil and canopy characteristics are spatially variable, both the pattern of soil moisture and the associated outflow must be represented in modelling these processes. This study compares implicit and explicit routing approaches to modelling the evolution of soil moisture pattern and spatially variable runoff production. It also addresses the implications of using different landscape partitioning strategies. This study presents the results of calibration and application of these different routing and landscape partitioning approaches on a 60 ha forested watershed in Western Oregon. For comparison, the different approaches are incorporated into a physically based hydro-ecological model, RHESSys, and the resulting simulated soil moisture, runoff production and sensitivity to unbiased error are examined. Results illustrate that both routing approaches can be calibrated to achieve a reasonable fit between observed and modelled outflow. Calibrated values for effective watershed hydraulic conductivity are higher for the explicit routing approach, which illustrates differences between the two routing approaches in their representation of internal watershed dynamics. The explicit approach illustrates a seasonal shift in drainage organization from watershed to more local control as climate goes from a winter wet to a summer dry period. Assumptions used in the implicit approach maintain the same pattern of drainage organization throughout the season. The implicit approach is also more sensitive to random error in soil and topographic input information, particularly during wetter periods. Comparison between the two routing approaches illustrates the advantage of the explicit routing approach, although the loss of computational efficiency associated with the explicit routing approach is noted. To compare different strategies for partitioning the landscape, the use of a non-grid-based method of partitioning is introduced and shown to be comparable to grid-based partitioning in terms of simulated soil moisture and runoff production. Copyright © 2001 John Wiley & Sons, Ltd. [source] Agricultural land use and Skylark Alauda arvensis: a case study linking a habitat association model to spatially explicit change scenariosIBIS, Issue 1 2010NIGEL D. BOATMAN The development of forward scenarios is a useful method of envisaging the environmental implications of potential changes in land use, as a tool for policy development. In this paper, a spatially explicit case study is used to provide insight into the environmental impacts of Common Agricultural Policy reform on Skylark Alauda arvensis, a species which is widespread on arable farmland, breeds in crops and has declined in recent decades. A generalized linear mixed model was used to estimate Skylark breeding population densities in different crops, using survey data collected from farms in the east of England, supplemented by the literature. Model outputs were then used to predict Skylark densities in an East Anglian Joint Character Area dominated by arable cropping. Predicted densities were mapped at field level using GIS, based on actual cropping derived from Integrated Administration and Control System data collected for the administration of subsidy payments. Three future scenarios were then created, based on expert opinion of potential changes in cropping over the next 5 years, and potential changes in Skylark density mapped on the basis of the predicted changes in cropping patterns. Overall, Skylark densities were predicted to decrease on average by 11,14% under ,market-led' (increasing wheat and oilseed rape, reduced set-aside) and ,energy crop' (5% area under short rotation coppice) scenarios, but remained virtually unchanged under an ,environment-led' (diverse cropping) scenario. The ,market-led' scenario is closest to short-term agricultural trajectories, but wider cultivation of biomass energy crops as modelled under the ,energy crop' scenario could occur in the medium term if energy policies are favourable. Appropriate mitigation strategies therefore need to be implemented if a continued decline in the Skylark population on lowland arable farmland is to be averted. The results provide a readily accessible visualization of the potential impacts of land-use change for policy-makers; similar techniques could be applied to visualize effects of changes arising through other drivers, including climate change. [source] Modification of growing-season surface temperature records in the northern great plains due to land-use transformation: verification of modelling results and implication for global climate changeINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2004Rezaul Mahmood Abstract Land-use and land-cover change can modify near-surface atmospheric condition. Mesoscale modelling studies have shown that modification in land use affects near-surface soil moisture storage and energy balance. Such a study in the Great Plains showed that changes in land use from natural grass to irrigated agriculture enhanced soil water storage in the root zone and increased latent energy flux. This increase in latent energy flux would correspond to a decrease in sensible heat flux and, therefore, modify near-surface temperature records. To verify this deduction, we have investigated the changes in the historical near-surface temperature records in Nebraska, USA. We have analysed the long-term mean monthly maximum, minimum, and monthly mean air temperature data from five irrigated and five non-irrigated sites. The cooperative weather observation (coop) network is the source of the data. We have found that there is a clear trend in decreasing mean maximum and average temperature data for irrigated sites. For example, York, NE, reports that the mean maximum growing season temperature is decreasing at the rate ,0.01°C year,1. The results from non-irrigated sites indicated an increasing trend for the same parameters. The data from Halsey, NE, indicate a +0.01°C year,1 increase in this century. In addition, we have conducted similar analyses of temperature data for the National Climatic Data Center's Historical Climatic Network data set for the same locations. The results are similar to that obtained with the coop data set. Further investigation of dew-point temperature records for irrigated and non-irrigated sites also show an increasing and decreasing trend respectively. Therefore, we conclude that the land-use change in the Great Plains has modified near-surface temperature records. Copyright © 2004 Royal Meteorological Society [source] The impact of land-cover modification on the June meteorology of China since 1700, simulated using a regional climate modelINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2003H. Wang Abstract A series of simulations was conducted using a regional climate model with a domain covering mainland China. Simulations were conducted for a single June using estimated land cover for 1700, 1750, 1800, 1850, 1900, 1950, 1970 and 1990. The conversion of land cover between these periods was extensive over mainland China, where large areas were altered from natural forests to either grass or crops, or from natural grasslands to crops. These land-cover modifications affect various characteristics of the land surface, which lead to changes in the way available energy and water are partitioned. Over areas where land cover was modified, substantial changes are simulated. The conversion from forests to grasses or crops leads to warming and to reductions in root zone soil moisture and latent heat fluxes. Regionally, the conversion from forest to grasses and crops leads to significant warming over large areas of China, but there is an area of cooling present that is coincident with the main location of a land-use change from short grass to crops. The changes in temperature propagate to about 1500 m above the surface and affect specific humidity throughout this part of the atmosphere. An analysis of daily average results shows a consistent impact of land-cover modification on temperature, latent heat flux and soil moisture. Therefore, we find large and consistent impacts over China resulting from historical land-cover modification that are sufficiently important to the regional-scale climate to warrant inclusion in future modelling efforts. Our results suggest that efforts to attribute warming patterns over China to any particular cause need to take into account the conversion of the land cover that has taken place over China over the last 300 years. Copyright © 2003 Royal Meteorological Society [source] Oilseed rape crops distort plant,pollinator interactionsJOURNAL OF APPLIED ECOLOGY, Issue 1 2010Tim Diekötter Summary 1. New incentives at the national and international level frequently lead to substantial structural changes in agricultural landscapes. Subsidizing energy crops, for example, recently fostered a strong increase in the area cultivated with oilseed rape Brassica napus across the EU. These changes in landscape structure affect biodiversity and associated ecosystem services. 2. Mass-flowering oilseed rape has been shown to positively affect colony growth and densities of bumblebees, which may enhance pollination services in agroecosystems. Not considered, however, have been species-specific traits of pollinators resulting in disproportionate benefits from these recurrent resource pulses. A subsequent community shift towards the subsidized species potentially distorts plant,pollinator interactions in the surrounding landscape. 3. We analysed the effects of mass-flowering crops on the abundance of legitimate long-tongued bumblebee pollinators, nectar robbing by illegitimate short-tongued bumblebees and seed set in the long-tubed flowers of red clover Trifolium pratense in 12 landscape sectors with differing amounts of oilseed rape. 4. Densities of long-tongued bumblebees visiting long-tubed plants decreased with increasing amounts of oilseed rape. The simultaneous increase of nectar robbing suggests that resource depletion is a likely explanation for this decline which may lead to a distortion in plant,pollinator interactions. The decline in long-tongued bumblebees, however, did not result in an immediate effect on seed set. In contrast, seed set increased with increasing amounts of semi-natural habitats, indicating the positive effects of these habitats on the legitimate long-tongued pollinators. 5.Synthesis and applications. Accounting for species-specific traits is essential in evaluating the ecological impacts of land-use change. The disproportional trait-specific benefits of increasing oilseed rape to short-tongued bumblebees may abet an increasingly pollinator-dependent agriculture but simultaneously threaten the more specialized and rare long-tongued species and their functions. Semi-natural habitats were found to positively affect seed set in long-tubed plants indicating that they can counteract the potentially distorting effects of transient mass-flowering crops on plant,pollinator interactions in agroecosystems. Future agri-environmental schemes should aim to provide diverse and continuous resources matching trait-specific requirements of various pollinators in order to avoid resource competition. Thereby they harmonize the economic interest in abundant pollinators and the conservation interest in protecting rare species. [source] Understanding the biodiversity consequences of habitat change: the value of secondary and plantation forests for neotropical dung beetlesJOURNAL OF APPLIED ECOLOGY, Issue 3 2008Toby A. Gardner Summary 1Secondary and plantation forests are becoming increasingly widespread in the tropics. A recent meta-analysis on the impacts of land-use change on tropical forest dung beetles concluded that regenerating forests can be effective in helping to offset species loss following deforestation. However, our understanding of the extent to which these results can be generalized to new locations remains very poor. 2We attempted to overcome many of the design limitations that characterize previous studies by collecting spatially independent dung beetle samples from primary, secondary and Eucalyptus plantation forests in north-east Brazilian Amazonia across a large quasi-experimental landscape that minimized confounding edge and fragmentation effects. 3We recorded 9203 dung beetles, comprising 85 species. Species richness was significantly higher in primary forest and the majority of species were more abundant there than elsewhere, whereas secondary and plantation sites harboured an impoverished subset of primary forest species. 4Our data illustrate the low value of tropical secondary and plantation forests for dung beetles in our study area, and our conclusions are more pessimistic than those of earlier studies. 5Because of differences in the order of species rank-abundance and rank-biomass patterns, re-coding community data from abundance to biomass significantly altered the analytical weight of individual species in determining community patterns. Larger bodied beetles were more prone to local extinctions and abundance declines and this effect was consistent both within and between genera. 6Synthesis and applications. Our study demonstrates that secondary and plantation forests in a large neotropical landscape host exceptionally impoverished dung beetle communities. Furthermore, the depletion of beetle abundance combined with a reduction in average body mass in converted forests is likely to have detrimental consequences for the maintenance of dung beetle-mediated ecosystem services in these habitats. Differences in biogeographical and landscape context, and the influence of common limitations in sampling design, may explain why many other studies have painted a more optimistic picture of the conservation value of anthropogenic habitats. In the absence of further evidence we caution strongly against the claim that forest regeneration schemes on degraded land can effectively offset the loss of species following deforestation, and urge that conservation strategies prioritize the protection of remaining areas of primary forest. [source] A regional impact assessment of climate and land-use change on alpine vegetationJOURNAL OF BIOGEOGRAPHY, Issue 3 2003Thomas Dirnböck Abstract Aim, Assessing potential response of alpine plant species distribution to different future climatic and land-use scenarios. Location, Four mountain ranges totalling 150 km2 in the north-eastern Calcareous Alps of Austria. Methods, Ordinal regression models of eighty-five alpine plant species based on environmental constraints and land use determining their abundance. Site conditions are simulated spatially using a GIS, a Digital Terrain Model, meteorological station data and existing maps. Additionally, historical records were investigated to derive data on time spans since pastures were abandoned. This was then used to assess land-use impacts on vegetation patterns in combination with climatic changes. Results, A regionalized GCM scenario for 2050 (+ 0.65 °C, ,30 mm August precipitation) will only lead to local loss of potential habitat for alpine plant species. More profound changes (+ 2 °C, ,30 mm August precipitation; + 2 °C, ,60 mm August precipitation) however, will bring about a severe contraction of the alpine, non-forest zone, because of range expansion of the treeline conifer Pinus mugo Turra and many alpine species will loose major parts of their habitat. Precipitation change significantly influences predicted future habitat patterns, mostly by enhancing the general trend. Maintenance of summer pastures facilitates the persistence of alpine plant species by providing refuges, but existing pastures are too small in the area to effectively prevent the regional extinction risk of alpine plant species. Main conclusions, The results support earlier hypotheses that alpine plant species on mountain ranges with restricted habitat availability above the treeline will experience severe fragmentation and habitat loss, but only if the mean annual temperature increases by 2 °C or more. Even in temperate alpine regions it is important to consider precipitation in addition to temperature when climate impacts are to be assessed. The maintenance of large summer farms may contribute to preventing the expected loss of non-forest habitats for alpine plant species. Conceptual and technical shortcomings of static equilibrium modelling limit the mechanistic understanding of the processes involved. [source] Ecological gradients as a framework for analysis of land-use change in East AfricaAFRICAN JOURNAL OF ECOLOGY, Issue 2009A. E. Majule Abstract This paper discusses the ecological gradient as an organizing framework to assist understanding the complex interactions between societal and ecological processes underlying land-use change in East Africa. Detailed case studies on the gradients of the slopes of Mt Kilimanjaro, Kenya show how land-use change is responsive to the dynamics of both local and external driving forces. The study has shown that the distinct ecological conditions at the extremities of gradients are associated with specific land uses which may be different within livelihood systems such as for wet and dry season grazing. Access to water for cultivation, domestic use, livestock and wildlife is critical in determining the nature and distribution of livelihood systems. Land-use systems interact across the different ecological zones of the gradients characterized by vigorous spatial, cultural and economic interactions. Sometime conflicts occur between or within land-use/livelihood systems. There is strong evidence that the areas of higher economic potential remain advantaged compared with areas lower on the gradient. The ecological characteristics have been found to influence human activities and distribution. Interactions between societies are important in terms of trade, social relations and access to resources. [source] Interactions between non-native plant species and the floristic composition of common habitatsJOURNAL OF ECOLOGY, Issue 6 2006L. C. MASKELL Summary 1We investigated the role of non-native species (neophytes) in common British plant communities using botanical data from two stratified random surveys carried out in 1990 and 1998. 2We found that from 16 851 plots surveyed in 1998 there were 123 non-native species found mostly in arable, tall grass/herb and fertile grassland habitats. Invasive non-native species, e.g. Fallopia japonica, Impatiens glandulifera and Rhododendron ponticum, were uncommon in this survey. 3Between 1990 and 1998 the total number of non-native species increased but the mean number of species per sample plot decreased. The mean cover of non-natives increased from 1.2% to 1.9%. 4There were positive spatial and temporal relationships between non-native and native species diversity. However, there was a weak negative relationship between changes in non-native cover and native diversity. 5The species composition and ecological traits of communities containing non-natives were very different from those that did not contain them. 6In the British countryside non-native species were mainly found in habitats with anthropogenic associations, high fertility, high number of ruderal species and high diversity. There is also an indication that successional shifts where competitive invasive species dominate involve non-native species. 7National-scale changes in plant community composition are likely to be closely correlated with external land-use impacts. Changes such as eutrophication, nitrogen deposition and increased fertility in infertile habitats are likely to benefit both native and non-native invasive species; however, currently these trends benefit native species much more often than non-natives. 8Non-native species are known to have significant effects on native species at local scales in many countries; however, at the landscape scale in Great Britain they are best considered as symptoms of disturbance and land-use change rather than a direct threat to biodiversity. [source] NATURAL RESTABILIZATION OF STREAM CHANNELS IN URBAN WATERSHEDS,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2000Patricia C. Henshaw ABSTRACT: Stream channels are known to change their form as a result of watershed urbanization, but do they restabilize under subsequent conditions of constant urban land use? Streams in seven developed and developing watersheds (drainage areas 5,35 km2) in the Puget Sound lowlands were evaluated for their channel stability and degree of urbanization, using field and historical data. Protocols for determining channel stability by visual assessment, calculated bed mobility at bankfull flows, and resurveyed cross-sections were compared and yielded nearly identical results. We found that channel restabilization generally does occur within one or two decades of constant watershed land use, but it is not universal. When (or if) an individual stream will restabilize depends on specific hydrologic and geomorphic characteristics of the channel and its watershed; observed stability is not well predicted by simply the magnitude of urban development or the rate of ongoing land-use change. The tendency for channel restabilization suggests that management efforts focused primarily on maintaining stability, particularly in a still-urbanizing watershed, may not always be necessary. Yet physical stability alone is not a sufficient condition for a biologically healthy stream, and additional rehabilitation measures will almost certainly be required to restore biological conditions in urban systems. [source] | |||||||||||||||||||||||||||||||||||||